sub _prepare_addresses {
  my ($self, $type) = @_;
  if (ref $self->{$type}) {
    $self->{$type.'_list'} = $self->{$type};
    $self->{$type} = join ', ', @{$self->{$type.'_list'}};
  } else {
    $self->{$type} =~ s/\s+/ /g;
    $self->{$type} =~ s/, ?,/,/g;
    $self->{$type.'_list'} = [map {s/\s+$//;$_} $self->{$type} =~ /((?:[^"',]+|"[^"]*"|'[^']*')+)(?:,\s*|\s*$)/g];
  }
}